Refrigerating apparatus



April 9, 1946. R. H. SWART REFRIGERA'I'ING APPARATUS Filed March 20,1944 FIGQI.

INVENTOR.

RICHARD H.5WART ATTORNEYS Patented Apr. 9, 1946 UNITED STATE s PATENTOFFICE This invention relates generally to refrigerating apparatus andrefers more particularly to an improved device for controlling the flowof the refrigerating medium or liquid refrigerant from the receiver ofthe condenser to the evaporator or cooling unit of the apparatus.

One of the essential objects of the invention is to provide a device ofthe type mentioned that may be utilized in place of and has advantagesover an expansion valve or a float structure or a capillary tube forcontrolling the flow of the re- For exfrigerating medium to theevaporator. ample, the commonly used thermostatic expansion valve ismore expensive to manufacture, has 7 more moving parts and is apt tohave leaks at the evaporator, with the result that'there is an importantdecrease in refrigeration efiiciency and cooling capacity of theevaporator just at a time when it is needed most. At' lower roomtemperatures than the specific conditions permitting correct feed, suchtubes pass insufficient refrigerant for eflicient operation. Floatvalves, and expansion valves which are also commonly used for feedingrefrigerants, require-a multiplicity of accurately fabricated partswhich are expensive. and subject to wear and frequently need repairorreplacement. Thus, the conventional devices mentioned are unsatisfactoryor expensive to install and repair. 1

Another object is to provide a device having elements formed ofmaterials provided with different thermal coefficients of expansiondisposed in heat exchange relation to the return or suction conduit forthe refrigerating medium flowing from the evaporator to the compressorso that slight variations in the temperature of the suction conduit willcause relative movement between the elements of, the device. r

The capillary tubes 7 Another object is to provide a device wherein oneof the elements just mentioned is preferably in the form of a tube orconduit for the refrigcrating medium flowing from the receiver of the66- condenser to the evaporator and serves as a valve seat for a valvecarried by the other of said ele ments, so that the action of the valveto control the flow of refrigerating medium to the evaporator isresponsive to relative movement between such elements.

Another object is to provide a device which will unload'the compressorat the start of a cooling cycle, by permitting the suction pressure anddischarge pressure to equalize.

Another object is to provide a, heat exchange between the warm liquidrefrigerant entering the device and the cold suction vapor returningfrom the evaporator in order to sccurehigh thermodynamic efllciency fromthe refrigeration system.

Another object is to provide a device for limiting the suction pressureof the compressor to a value below which the motor is not overloaded.

Another object is to provide a device that is simple in construction,economical to manufacture, easy to install and efficient in operation.

Other objects, advantages and novel details of construction of thisinvention will be made more apparent as this description proceeds,especially when considered in connection with the accompanyingdrawing-wherein:

Figure 1 is a diagrammatic view of refrigeratiim apparatus having adevice embodying my invention;

Figure 2 is an enlarged fragmentary vertical sectional view through thereturn conduit and the device embodying my'invention;

Figure 3 is a sectional view taken substantially on the line 3-3 ofFigure 2;

Figure 4 is a sectional view taken substantially on the line 4-4 ofFigure 2;

Figure 5 is a view similar to Figure 3 but showing a slightmodification.

Referring to the drawing, A is a device em- H, and J is a conduit forthe refrigerating medium flowing from the compressor H to the condenserD.

As shown, the device A is in heat exchange relation to the returnconduit F and preferably comprises a tube IU of stainless steel or othersuitable material of low thermal expansion, a rod or wire ll of copperor other suitable material of high thermal expansion, and a valv I! onthe rod I l and engageable with the 'adiacent end l3 of the tube Hi tocontrol the flow of refrigerating medium from the tube iii to theevaporator E.

Preferably the tube III telescopically engages and is terminallyconnected to adjacent sections of the conduit B, while the rod I Iwithin said tube is fixed or anchored at its forward end to the tube illbut otherwise is free with respect thereto. At its free rear end the rodII is threaded to permit adjustment thereon of the valve I2 so that suchvalve may be adjusted properly relative to its seat l3 at the adjacentend of the tube.

The forward end H of the rod may be flattened and soldered to a bellshaped portion I5 of the tube III, as illustrated in Figure 3, or may befixed to a spider-like sleeve l6 rigid with the tube It, as illustratedin Figure 5. In fact, any suitable rigid connection between the forwardend of the rod II and the tube I0 may be employed, as desired.

In use, the tube It ofthe device is soldered or otherwise secured inthermal contact with the return conduit F throughout substantialportions of their length, as illustrated in Figure 1 so that such tubeIII will be in thermal contact with said conduit. Thus, the tube I 0serves as a heat transfer element between the return conduit F and theliquid flowing through conduit I0, thence to rod II. The rod II willtherefore change in length with respect to conduit It as influenced bychanges in temperature of the return vapor in conduit F. In arefrigeration system it is necessary to control the "superheat of thesuction vapor in the evaporator outlet conduit to obtain eflicientperformance of the system. If the temperature of the vapor is at orslightly above the evaporating temperature of the refrigerant, thepresence of unevaporated liquid is indicated. If the temperatureof thevapor is abnormally high, the evaporator surface is inadequatelyutilized. Therefore, my device permits end of the tube I3 will berelatively great. This permits a greater rate of liquid refrigerant flowto the evaporator, resulting in the vapor superheat in conduit Fdecreasing. In case the Vapor becomes cooler than the desired superheat,the

conduit F receives additional heat from the inopen ended tubing having across section less than that of said feed conduit and extendingthroughout the ma! or portion of its length lengthwise of and in thermalcontact throughout substantially its entire length with the exterior ofsaid return conduit, said tubing of less cross section forming a part ofsaid feed conduit for conducting refrigerating medium from the condenserto the evaporator, and means for modifying the output of said tubing ofless cross section including a valve at the outlet end of said tubing,and an actuating rod for said valve fixed to said tubing at the inletend thereof, said rod and tubing being formed of materials havingdifi'erent thermal coefficients of expansion so that a differential inexpansion and contraction of said elements is obtained under varyingtemperature con-. ditions of said return conduit.

2. In a refrigerating apparatus of the compressor-condenser-evaporatortype, the combination with a return conduit for conducting refrigeratingmedium from the evaporator to the compressor, of a feed conduit forconducting refrigerating medium from the condenser to the evaporator andincluding as a part thereof a double restrictor structure forcontrolling the flow of refrigerating medium to said evaporator, saiddouble restrictor structure comprising a single length of open endedtubing having an outwardly flared inlet end and provided from saidflared inlet end to its outlet end with a restricted coming liquidrefrigerant, lowering the temperature of the liquid, the conduit ID andthe rod I I.

As the conduit!!! androd ll cool, the rod II shortens with respect totube'lfl, causing the valve I2 to move closer to seat I3, therebyrestricting the rate of liquid flow. Thus, a subpressor, of a doublerestrictor structure in an evaporator feed conduit for controlling theflow of refrigerating medium from the condenser to the evaporator andcomprising a single length of passage for the refrigerating medium, saidtubing extending throughout the major portion of its lengthlengthwise ofand in thermal contact throughout substantially its entire length withthe exterior of said return conduit, and means for modifying the outputof said tubing, including a valve at the outlet end of said tubing, andan actuating rod for said valve extending therefrom through therestricted passage aforesaid of said tubing and fixed to the flaredinletof said tubing, said rod and tubing being formed of materials havingdiiferent thermal coemcients of expansion so thata differential inexpansion and contraction of said elements is obtained under varyingtemperature conditions of said return conduit. p

3. In a refrigerating apparatus of the compressor-condenser-evaporatortype, the combination with a return conduit for conducting refrigeratingmedium from'the evaporator to the compressor, of a feedconduit forconducting refrigerating medium from the condenser to the evaporator andincluding as a part thereof a double restrictor structure forcontrolling the flow of refrigerating medium to said evaporator, saiddouble restrictor structure comprising a single length of open endedtubing provided throughout substantially its entire length with arestricted passage for the refrigeratin medium, said tubing extendingthroughout the major portion of its length lengthwise of and in thermalcontact throughout substantially ,its entire length with the exteriorofsaid return conduit, and means for modifying the output of saidtubing, including a valve at the outlet end of said tubing, and, anactuating rod for said valve extending therefrom through the restrictedpassage aforesaid oi said tubing and fixed to the said tubing at theinlet end thereof, said rod and tubing being formed of materials havingdifferent thermal coefficients of expansion so that a differential inexpansion and contraction of said elements is obtained under varyingtemperature conditions of said return conduit.

said open ended tubing, including a valve at the outlet end of saidtubing. and an actuating rod 4. In a refrigerating apparatus of thecompressor-condenser-evaporator me. the combination with a returnconduit for conducting refrigerating medium from the evaporator to thecompressor, of a feed conduit for conducting refrigerating medium fromthe condenser to the evaporator and including as a part thereof a doublerestrictor structure for controlling the flow of refrigerating medium tosaid evaporator, said double restrictor structure comprising a single 1length of open ended tubing extending throughout the major portion ofits length lengthwise of and in thermal contact throughout substantiallyits entire length with the exterior of 'said return conduit, and meansfor modifying the .output of 16 for said valve attached thereto at theoutlet end of said tubing, said rod extending through and cooperatingwith the interior ofsaid tubing to form therein a passage of less crosssection than said feed conduit, said rod being fixed to said tubing atthe inlet end thereof, said rod and tubing being formed of materialshaving dif- RICHARD svvART.

